1. Field of the Invention
The invention relates to a manufacturing method for a semiconductor device.
2. Description of Related Art
In a manufacturing method for a semiconductor device using a SiC substrate, heat treatment is carried out in order to, for example, activate an impurity introduced into the SiC substrate. During the heat treatment, sublimation of Si (silicon) on a surface of the SiC substrate happens, which can cause deterioration of flatness of the surface of the SiC substrate. In a manufacturing method for a semiconductor device described in Japanese Patent Application Publication No. 2001-068428 (JP 2001-068428 A), a photoresist layer is formed on a surface of a SiC substrate before carrying out heat treatment of the SiC substrate. Once the SiC substrate is heat-treated, the photoresist layer is carbonized, and a graphite layer is formed. The graphite layer works as a protective coat during heat treatment. Therefore, sublimation of Si on the surface of the SiC substrate is restrained.
However, the photoresist layer contains components other than carbon, such as oxygen and sulfur. While oxygen, sulfur and so on are lost from the photoresist layer, carbon remains, thereby forming the graphite layer. Thus, density of carbon present inside the graphite layer is relatively low. As a result, heat resistance of the graphite layer may not be sufficient.